for MBBS undergraduate students

1. Dr. Abhijeet
Mane
Assistant
Professor
Department of
Microbiology
BVDUMC, Pune
ACTINOMYCETES

2.  Diverse group
 Gram positive
 Non-motile
 Non-sporing
 Non-capsulated
 Bacilli
 Arranged in chains or branching filaments
 Related to Mycobacteria and Corynebacteria
 Most are soil saprophytes or normal human
commensals
INTRODUCTION

3. Important genera include
Actinomyces
Nocardia
Actinomadura
Streptomyces
Thermophilic
INTRODUCTION (CONTD.)

4.  Actinomyces
 Anaerobe, non acidfast
 Produce actinomycosis
 Nocardia
 Aerobe, acid fast
 Cause actinomycetoma and pulmonary infection
 Actinomadura
 Aerobe, non acid fast
 Cause actinomycetoma
 Streptomyces
 Aerobe, non acid fast
 Thermophilic
 Micropolyspora and Thermoactinomyces
INTRODUCTION (CONTD.)

5.  Soil saprophytes and commensals of oral cavity
 In humans they cause actinomycosis
 A.israelli – most common
 A.naeslundii and A.odontylyticus - rare
ACTINOMYCES

6.  Chronic suppurative, granulomatous infection
 Characterised by multiple abscess with discharging sinuses
 Discharge contains granules
 Later fibrosis and tissue destruction
 Name refers to ray-like appearance of organism in the
granules (Actinomyces, meaning ray fungus)
PATHOGENESIS

7.  Mode of infection
 Since commensals, endogenous infection and may result from
trauma eg. Dental extraction
 Bacteria bridge mucosal surface of mouth, grow in anaerobic
niche, induce a mixed inflammatory response
 Form painless indurated swelling with discharging sinuses
 Discharge contains granules
PATHOGENESIS (CONTD.)

8.  Cervicofacial actinomycosis: MC form
 Usually presents as painless, slow growing, hard mass with
cutaneous fistulas ….. Lumpy Jaw
 Other rare forms:
 Abdominal
 Pelvic
 Disseminated
CLINICAL MANIFESTATIONS

9.  Specimen
 Discharge from sinuses or fistula
 Rarely BAL, sputum or tissue sections
LABORATORY DIAGNOSIS

10.  Direct Microscopy
 Pus discharge thoroughly washed in saline in a test tube
 Sediment – gritty, white or yellowish sulphur granules of
<5mm size
 Granules crushed between 2 slides and smears made
LABORATORY DIAGNOSIS (CONTD.)

11.  Gram staining (Brown-Brenn modification)
 Shows central mass of gram positive filamentous bacilli,
radiating peripherally with hyaline, club shaped ends
 Granules are hard and not emulsifiable (differentiating factor)
 Other methods – F Ab techniques
 FISH techniques
LABORATORY DIAGNOSIS (CONTD.)

12.  Histopathology
 HE and GMS – sun ray appearance
 Anaerobic Culture
 At 37 Deg C on media
 Thioglycollate broth – growth of A.israelli resembles fluffy balls at
bottom of tube
 BHI agar – spidery colonies after 48 hrs which enlarge and heap up
in 10 days
LABORATORY DIAGNOSIS (CONTD.)

13.  Penicillin – DOC x 6-12 months duration to prevent relapse
 If allergy, Erythromycin or tetracycline
 Sx removal if extensive lesions
TREATMENT OF ACTINOMYCETES

14.  Named after Edmond Nocard, 1898
 Gram positive branching filamentous bacilli similar to
Actinomyces
 Environmental saprophytes in soil and vegetations
 >50 species identified, 9 associated with human disease
 N.asteroides and N.brasiliensis MC pathogens
NOCARDIA

15.  Occurs worldwide, more in adult males
 Soil is natural habitat
 Infection acquired by
 Inhalation of fragmented bacterial mycelia
 Pulmonary nocardiosis
 Transcutaneous inoculation of bacteria
 Various cutaneous and subcutaneous manifestations (mycetoma)
 N.brasiliensis, N.asteroides
 Person-to-person spread not known
PATHOLOGY AND PATHOGENESIS

16.  Characteristic histologic feature -
 abscess with extensive neutrophil infiltration and prominent necrosis,
surrounded by granulation tissue
 Risk factors:
 CMI important in host
 Opportunistic infection
 AIDS, corticosteroid therapy, organ transplant, etc
PATHOLOGY AND PATHOGENESIS
(CONTD.)

17.  Pulmonary Nocardiosis
 Lobar pneumonia MC
 Subacute cough, thick, purulent sputum
 Pericarditis, mediastinitis, laryngitis rare
 Extrapulmonary (Disseminated) Nocardiosis
 Dissemination occurs via blood
 Brain abscess MC
 Followed by skin, bone, muscle
CLINICAL MANIFESTATIONS

18.  Mycetoma is chronic granulomatous condition affecting
subcutaneous tissues of feet and hands characterised by
 Subcutaneous nodular swelling
 Multiple sinuses
 Discharge contains granules
 Tendency to spread to adjoining bones
ACTINOMYCETOMA

19.  Mycetoma
 Affects tropical countries
 Organism enters through skin trauma
 Contaminated soil
 Broadly, Mycetoma is
 Eumycetoma
 Actinomycetoma – caused by Nocardia, Actinomadura, Streptomyces
somaliensis
ACTINOMYCETOMA (CONTD.)

20.  Specimen
 Depending upon site – sputum, pus, granules
 Granules in discharge are collected in sterile gauze or loop by
pressing sinuses
LABORATORY DIAGNOSIS

21.  Direct Microscopy
 HPE – multilobulated with
sun ray appearance
 Gram staining (Brown Brenn
modification)
 Gram positive branching,
filamentous bacilli of width
0.5-1.0 um
 Stain irregularly as filaments
beaded
 Modified Acid-fast staining
–
 using 1% H2SO4 as
decolouriser (Kinyoun method)
– Nocardiae are partially AF
appearing branching and
filamentous red coloured AFB
 Granules – micro colonies
composed of branching
filamentous bacilli
LABORATORY DIAGNOSIS (CONTD.)

22.  Culture
 Nocardia obligate aerobes
 Grow on BHI, SDA at 37 deg C x 2 days – 2 weeks
 Colonies - creamy, wrinkled, pigmented (orange or pink
colored), adhere firmly to medium
 Some have cotton wool ball appearance
LABORATORY DIAGNOSIS (CONTD.)

23.  Recovery of Nocardia from samples containg Actinomadura
and Streptomyces:
 Selective media
 Buffered yeast extract containing polymyxin and vancomycin
 SDA with Chloramphenicol
 Paraffin bait technique
 LJ medium – moist glabrous colonies
LABORATORY DIAGNOSIS (CONTD.)

24.  Biochemical identification
 Non motile, catalase positive, oxidative
 Decomposition of casein, hypoxanthine, tyrosine
 Growth in lysozyme
 Acetamide utilization
LABORATORY DIAGNOSIS (CONTD.)

25.  Sulfonamides – DOC
 Cotrimoxazole – alternative
 Rx duration –
 6-12 months – P, EP forms
 2 months – cellulitis
 Aspiration / drainage of abscess to limit spread
TREATMENT

26.  Most frequent cause of Actinomycetoma
 Actinomadura madurae and A. pellettieri
 Granules – white to yellow, except A. pellettieri produce red
coloured granules
 Colonies – molar tooth appearance after 48 hrs incubation
 Rx – susceptible to Amikacin and Imipenem
ACTINOMADURA

27. Thank you!!